Excessive exposure to vibration is known to cause a health problem known as “white finger” that causes numbness and pain and, for this reason there is a European Directive that specifies the maximum exposure levels that are considered safe.
A battery powered instrument described in our patent specification GB2413189 is held between the fingers of one hand and measures the cumulative exposure of the user to vibration from equipment that the user is holding. Instruments for measuring cumulative vibration exposure will be referred to in this specification as ‘dosimeters’. The dosimeter described in GB2413189 is convenient to use, accurate and reliable. However, there are some problems. Firstly, it has been found that it is important, for reasons of comfort, for the dosimeter to properly fit the user's hand. The fit needs to be sufficiently good that a single size of dosimeter cannot satisfactorily be used by all workers on a site. Secondly, on a site where there are many workers needing to use vibrating equipment, there is an administrative problem in assigning a dosimeter of the correct size, and that is known to be fully charged, to each worker before a work shift, collecting the dosimeter at the end of the shift, transferring the data on that dosimeter onto a computer in association with the identity of the worker, and then re-charging the dosimeter.
This invention resides partly in the recognition of the above problems and partly in the provision of a solution.